Telephone system.



0. L. GooDRUM. TELEPHONE SYSTEM. APPLICATION FILED MAE. 15, 1902.

1,043,314. Patented Nov. 5, 1912.

M www COLUMBIA PLANouRAPM co.,w^sH|NG1-0N. D. c.

sus

CHARLES L. GOODRUIVI, OF ATLANTC CITY, NEW JERSEY, ASSIGNOR, BY MESNEAS; VSI(rNlViEN'JIS, TO STROIVIBERG-CARLSON TELEPHONE MANFACTURINGCOMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.V

TELEPHONE SYSTEM;

Specification of Letters Patent.

Patented Nov. 5,1912?.

Application led March 15, 1902. Serial No. 98,304.

VTo all whom 'it may concern:

Be it known that I, CHARLES L. GrooDnUM, a citizen of the United States,residing at Atlantic City, county of Atlantic, and State of New Jersey,have invented certain new and useful Improvements in Telephone Systems,of which the following is a specification.

My invention relates to telephone systems of the complete metalliccircuit and central energy type. in systems of this character it isusual to provide complete metallic circuits between sub-stations and acentral exchange. It is also the practice to operate the varioussigna-ls, as for example, the line and supervisory signals at a centralexchange, and also the bells at the subscribers stations, by currentfrom suitable sources of supply located at the central station. At thecentral exchange the switch-board is provided with what are commonlyknown as jacks, each jack being co-nnected with a subscribers line. Thecentral operator is usually provided with a connecting` medium,preferably in the form of a cord having two or more strands provided ateach end with a plug. These plugs are adapted for insertion inthe jacks,so as to establish co-nnection between the lines of any two subscribers.Ordinarily the operator is provided with a generator for ringing thebells at the sub-stations. The line and supervisory signals are operatedby current supplied from the common battery at the central station. Whenthe subscriber sends in a call the line signal is operated, so as toattract the attention of the central operator, and the latter, afterlearning the number of the subscriber desired, makes the connection withthe plugs and 'cord circuit. When the subscribers at the substation hangup the receivers the supervisory signals are brought into operation andthe central operator is, in this way, advised that the subscribers arethrough talking. The common battery at the central exchange is soarranged as to supply current over the lines to the microphonetransmitters at the sub-stations. In this way, as stated, the current,both for talking and calling purposes, is supplied entirely from one ormore batteries or generators located atthe central exchange. rlhe lineand supervisory signals are usually in the form of small incandescentlamps, arranged in position to be easily observed by the centraloperator. The circuits for these lamps are automatically closed byrelays, which are energized or deenergized, as the arrangement mayrequire, by the closing or opening of the line circuits.

Generally stated, it is the objectof my invention to provide a simpleand highly efficient telephone system of the foregoing character.

A special object is to provide a simplified and improved arrangement ofcircuits and apparatus for operating the line signals.

It is also an object to provide certain details and features ofimprovement tending to increase the general efficiency, and to render asystem of this character more serviceable and satisfactory in use.

To the foregoing and other useful ends my invention consists in mattershereinafter set forth and claimed.

The accompanying drawing is a diagram illustrating a telephone systemembodying the principles of my invention.

In this diagram it will be observed that only two subst-ations togetherwith a cord circuit and line connections are shown, and

`it will be understood that only such instruments and apparatus areillustrated as are necessary to a full understanding of the invention.

As far as the construction of the system is concerned, it will bereadily understood that the system comprises any suitable number ofsub-stations equipped with subscribers apparatus of any suitable orapproved character. For example, the subscribers apparatus may besubstantially of the character shown at sub-stations A and B, thesesubstations being connected with the exchange or central station in anysuitable manner.

`Preferably, however, complete metallic line connection is employedbetween the substations and the switch-board apparatus at the exchangeor central station. Also, it will be readily understood that the batteryshown at the central station or exchange is adapted to furnish currentfor both talking and signaling purposes that is to say, this batteryfurnishes the current for both operating the line and supervisorysignaling apparatus, and for charging the transmitters at thesub-stations. As illustrated, the subscribers lines terminate in springjacks of a character hereinafter mo-re particularly described, thesespring jacks being mounted in any suitable manner on the switchboard atthe central station. Also, as shown, the switch-board apparatusincludesany suitable number of cords or operators cord circuits, each cord beingprovided with plugs adapted for insertion in the said jacks; and it willalso be seen that the line relays and the line signals are associatedwith the lines, while the supervisory signals and supervisory relays areassociated with the cord circuits. The different circuit arrangements,and the functions of the different devices, will, however, be moreclearly understood by considering the various connections and operationswhich take place in connecting up one subscriber with another. Thereforeas thus illustrated, and assuming that the subscriber at sub-station Adesires connection with a subscriber at substation B, the operation andcircuit connections which take place are as follows: `When the receiveris removed from the hookswitch at substation A, a circuit is closed frombattery 1 through conductor 2, through the switch-spring 3 and contactpoint 4, thence through conductor 5, through the transmitter 6, throughthe receiver 7, thence through the contact point 8, and the hookswitch9, through the line conductor 10, through the coil 11 of the line relayR, thence through contact point 12 and switch-spring 13, and throughconductor 14 to said battery. The current flowing through this closedline circuit energizes the relay R, causing the latter to attract itsarmature. The said armature when attracted closes a short local circuitfrom battery 1 through conductors 2 and 15 through the armature 16, thecontact point 17, thence through conductor 18, through the line lampsignal 19, conductors 2O and 21, and through conductor 14 to saidbattery. This lights the line lamp signal 19, thereby advising thecentral operator that the subscriber at substation A has sent in a call.The central operator then inserts the answering plug P of the cordcircuit in the jack J, so as to establish connection between the callingsubscribers line and the operators talking set in the cord circuit. Theinsertion of the answering plug in the jack in this manner completes ashort local circuit from the battery 1 through the conductors 14 and 21,through the coil 22 of the cut-out relay R1, through conduct-or 23,through the tip spring 24 of the jack, thence through the tip contact 25of the plug, through the cord strand 26, through the coil 27 of thesupervisory relay R2, thence through conductor 28 and the winding 29 ofthe repeating coil, and thence through conductors 30 and 2 to saidbattery. This energizes both the cut-out relay R1 and the supervisoryrelay R2. The relay R1 attracts its armature r, thereby opening the twoswitch-points controlled by the switchsprings 3 and 13, and in this waysevering the direct connection between the battery and the line. This,it will be observed, serves to denergize the relay R, and the latter inreleasing its armature opens the switchpoint in the circuit of the lamp19. 1n this way the insertion of the answering plug op crates toautomatically extinguish or restore the line signal. It will also beseen that when the answering plug is thus inserted, a line circuit isclosed fromv the battery 1 through the conductor 31, through the winding32 of the other repeating coil, through the conductor 33, thence throughthe coil 34 of the supervisory relay R3, through the cord strand 35, thesleeve 36 of the plug, thence through the thimble or ring 37 of thejack, through the line conductor 5, through the transmitter 6 andreceiver 7, through the contact point 8 and hook-switch 9, thencethrough the line conductor l0, through the contact spring 38 of thejack, through the tip contact 25 of the plug, through the cord strand26, through the relay R2, through the conductor 28 and the repeatingcoil winding 29, thence through the conductors 30 and 2 to said battery.The energization of the relay R3 by the closing of the line circuitcloses a normally open shunt connection around the relay R2, consistingof the conductor 39, the armature 40, contact .point 41 and theconductor 42. This denergizes the relay R2, and prevents the latter fromattracting its armature and thereby closing the circuit of thesupervisory lamp. In this way, when the answering plug is inserted, therelay R3 is made a part of the line circuit and the relay R2 is made apart of such line circuit and also a part of a local circuit. At thisjuncture, it will be understood that the operator communicates with thecalling subscriber in any suitable manner as, for example, by pressingan ordinary listening key, so as to bridge the operators talking setacross the cord circuit, in the usual manner. After learning the numberof the substation desired, the operator then inserts the calling plug P1in the jack J1. The operator also then presses the ringing key,rso as tobridge the generator across the cord circuit, and then by operating thegenerator ringing current is projected onto the line of the called forsubscriber, for the purpose of ringing the bell at the latterssub-station. At this juncture, it will be seen that the line has beenput into proper condition to permit the operation of the generator bythe severing of the connect-ion between the battery and the line, due tothe energization of the cut-off relay R4.

lVhen the calling plug P1 is inserted a local circuit is completed fromthe battery thii'ough the conductors 2 and 30, through the winding 43 ofthe repeating coil, through conductor 44, through coil 45 of thesupervisory relay R5, through the conductor 4G., through the spring 47of the listening key, through the cord strand 48, through the plug tip49, through the tip spring 50 of the jack, thence through the conductor51, through the coil 52 'of the cut-out relay R4, thence through theconductors 53 and 14 to said battery. This energizes the supervisoryrelay R5 and, as stated, also energizes the cut-out relay R4. The latterin attracting its armature r1 opens the normally closed switch-points inthe connection between the battery and the line, thereby giving a freecircuit for the projection of the ringing current. r1`he energization ofthe supervisory relay R5 causes its armature to close a local circuitfrom the battery through the conductors 31 and 54, through the armature55, contact point 5G and the conductor 57, through the lamp 58, throughconductors 59 and 30, and through conductor 2 to said battery. rlhslights the supervisory lamp 58, and the said lamp remains lighted untilthe called for subscriber answers the call. When the subscriber atsubstation B removes the receiver from the hook-switch, a line circuitis completed from the battery through conductors 2 and 30, through thewinding 43 of the repeating coil, through conductor 44, through the coil45 ot the relay. R5, through the conductor 46, through the key spring 47and the cord strand 48, thence through the plug tip 49 and the jackspring 60, through the line conductor (3G, through the hook-switch 65and the contact point 64, thence through the receiver 63 and thetransmitter' 62, through the line conductor 61 and the ring or thimble67 of the jack, through sleeve contact 68 et the plug, through cordstrand 66, through key-springiO and'conductor 71 and key-spring '72,through contact point 73 and conductor 74, thence through the coil 7 5of the supervisory relay RG, through the winding 76 of the repeatingcoil, through conductors 77, 31 and 14 to the said battery. This, itwill be seen, energizes the relay RG, causing the latter to attract itsarmature and close a normally open shunt around the relay t5. Thisshunt, it will be seen, consists of a conductor 78, arn'iature 79,contact point 8() and conductor 81. The closing ot this shunt causes therelay R5 to release its armature, thereby opening the switch-point inthe circuit of the lamp 58, and thus eX- tinguishing the latter andadvising the operator that the called tor subscriber has answered thecall. The answering of the call at the sub-station B does not energizethe line relay R7, inasmuch as the connection between the battery andthe line has already been severed in the manner described. With bothplugs insert-ed, and with both receivers removed from the hooks at thesubstations,

the subscribers can communicate with each other, the talking circuitconsisting of the lines and the strands of the cord circuit. l,Vhile thesubscribers are talking, the current is furnished to the lines throughrepeating coils in the cord circuit. Vihen the subscribers hang up thereceivers at the sub-stations, relays R3 and RG are denergized, andrelease their armatures. Said armatures when released open t-he normallyopen shunts around relays R2 and R5, thereby allo-wing the latter tobecome energized. The said supervisory relays R2 and when energized,close the normally open switchpoints in the circuits of the supervisorylamps and cause the latter to glow and attract the attention of thecentral operator. Acting upon these signals, the central operator thenwithdraws the plugs of the cord circuit, and the system is then in itsnormal or disconnected condition, as shown in the drawing. Thus it willbe seen that the circuit arrangement for operating the lines or" thesupervisory signals is simple and efficient. At the saine time, thearrangement is characterized by substantially all ot the approvedmethods of operation. lt will be readily understood that the resistanceof the various coils and relays can be readily adjusted or regulated bythose skilled in the art, and in accordance with the conditions of anyparticular case.

The cut-out relays are, it will be observed, advantageously energizedthrough derived circuits including ditterentportions of the cord circuitconnections. in this way each derived circuit operates to hold thecut-out relay in operation as long as the plug is in the jack. f

That I claim as my invention is:

1. ln a telephone system, the combination of a subscriber-s line, abattery connected with the line through a normally closed switch, a linelamp signal, a line relay tor controlling the circuit of said line lampsignal, a cut-out relay arranged to operate said switch, a jackconnected with the line, a plug and a cord circuit, a supervisory lampand a supervisory relay associated with the cord circuit, one terminalof said cut-out relay being permanently connected with the battery, theother terminal of said relay being permanently connected with a tipContact of said jack, and the local circuit for said cut-out relay beingclosed by the insertion of the plug in the jack and including saidsupervisory relay.

2. ln a telephone system, the combination of a subscribers line, acentral source ot current supply connected with the line through anormally closed switch, a line lamp signal, a line relay for controllingthe circuit of said line lamp signal, a cut-out relay arranged tocontrol said switch, a jack having tip and sleeve contacts connectedwith the subscribers line, said jack also having a second tip contactconnected with one terminal of said cut-out relay, the other terminal ofthe cut-out relay being permanently connected with said source ofcurrent supply, a plug and a cord circuit, and a supervisory lamp andsupervisory relay associated with said cord circuit, the local circuitof said cut-out relay being closed by the insertion oit' the plug in thejack, and said local circuit including said supervisory relay.

3. In a telephone system, the combination of a subscribers line, acentral source of current supply connected with the line, a jackconnected with the line, a plug and a cord circuit, suitable connectionsfor supplying current from the central source of supply through thestrands of the cord circuits and the registering contacts of the plugand jack to said line, a supervisory relay in each strand of the cordcircuit, a supervisory lamp having a circuit cont-rolled by one ot' saidsupervisory relays, a normally open shimt around the relay arranged tocontrol the circuit of the supervisory lamp, said shunt being controlledby the other supervisory relay, a line lamp signal, a line relay forcontrolling the circuit of said line lamp signal, and a cut-out relay:tor severing the connection between said source of current supply andthe said line, the circuit for said cut-out relay including tip contactsof a jack and plug, and also including the supervisory relay whichcontrols the circuit of the supervisory lamp.

4. A telephone system comprising a line signal and a line relay foroperating the same, a cut-out relay for denergizing said line relay, asupervisory relay, a source of current supply with suitable connectionfor energizing all of the said relays, and a plug switch for closing thecircuit ot said cut-out relay, said switch having a plurality of tipcontacts in the jack, so as to restore the line signal, the circuit ofsaid cut-out relay including tip contacts of said switch.

5. In a telephone exchange system, telephone lines, a cord circuit, apair of supervisory relays included in said circuit, one at each sidethereof, a shunt or short circuit extending around one relay, controlledby the other relay, and a supervisory signal controlled by the onerelay.

6. In a telephone exchange system, telephone lines, a cord circuit, apair ot' supervisory relays included in said circuit, one at each sidethereof, a shunt or short circuit extending around one relay, controlledby the other relay, and a supervisory signal controlled by the onerelay, together with repeating coils included in the talking circuit,and energizing circuits for said relays, each energizing circuitincluding a repeating coil winding.

7. In a telephone exchange system, a cutoff relay for a telephone line,a supervisory relay, an energizing circuit including the two relays inseries, a short circuit around said supervisory relay also included insaid circuit, and a jack permanently connected with the line, saidrelays all energized over circuits including portions of the talkingcircuit.

8. The combination with a switchboard having terminal plugs providedwith a plurality of switch contacts, and containing two conductorselectrically uniting corresponding contacts of said plugs, a source ofcurrent in a bridge between said conductors, and two signal devicesassociated with said plugs respectively, of relay mechanism in thecircuits of said conductors and source of current controlling thecurrent supplied to said signaling devices, and two relays in circuitwith the said cord conductors one on either side of the said bridge, ofshunt circuits controlling said signals and controlled by said tworelays, thereby determining the display or withdrawal of said signals,substantially as set forth.

9. In a telephone system, a line, a relay, a normally open short circuitaround said relay, a second relay for closing said shunt, a line circuitfor energizing the said second relay, a local circuit for energizing thefirst mentioned relay, when connection is made to said line, and meansfor supplying battery current to the windings of both the said relaysand to the said line.

10. In atelephone system, a line, a relay, a normally open short circuitaround said relay, a second relay for closing said shunt, a line circuitfor energizing the said second relay, means for supplying batterycurrent to the windings of both the said relays and to the said line, aline signal, and a cut off relay having its winding included in saidlocal circuit.

l1. In a telephone system, the combination of calling and calledtelephone lines, an operators cord circuit Jfor connecting said lines, apair of relays for each end of said cord circuit, one member of eachpair of relays having a normally open shunt controlled by the otherrelay thereof, and a supervisory lamp for each pair of relays, saidrelays all energized over circuits including portions of the talkingcircuit.

12. In a telephone system, a line, a pair of relays, a normally openshunt around one relay cont-rolled by the other relay, a local circuitfor energizing the one relay, and a line circuit for the other or shuntcontrolling relay, said line circuit including the windings of the shuntcontrolling relay and the shunt around the other relay in series.

13. In a telephone system, a pair of relays, a line signal, a shuntaround one relay controlled by the other relay, a cut-oii relay forretiring the line signal, and a local circuit for energizing saidcut-oit relay in series with the winding of the shunted relay, saidrelays all energized over circuits including portions of the talkingcircuit.

14. A telephone system comprising a telephone line, a source of currentand a relay between the two limbs ot' said line, the source of currentin bridge of the talking circuit, a second relay and means forenergizing it, a switch at the substation and a switch at the centralstation for controlling the circuit through said relays, a signalcontrolled by the conjoint action of said relays, and a line signalcut-od1 relay for each line energized in series with one of said relays.

15. A telephone system comprising a telephone line, of a source ofcurrent and a relay between the two limbs of said line, whereby thesource of current is in bridge of the talking circuit, a second relayand means for energizing it, a switch at the substation for controllingsaid bridged relay and a switch at the central oflice for controllingsaid other relay, a signal controlled by the conjoint action of saidrelays, and a line signal cut-oitz relay for each line energized inseries with one of said relays.

16. A telephone system comprising a telephone line, of a source ofcurrent and an electro-magnet between the two limbs of said line,whereby the source of current is in bridge ofthe talking circuit, asecond electro-magnet and means for energizing it, a switch at thesubstation and a switch at the central station for controlling thecircuit through said electro-magnets, a supervisory signal controlled bythe joint action of said electro-magnets, and a line signal cut-oillrelay for each line energized in series with one of said relays.

17. A telephone line, a source of electricity and a pair of relaysbetween the limbs of said line, whereby the source of current is inbridge of the talking circuit, a switch at the substation and a switchat the central station for controlling the circuit through said relays,a signal adapted to be controlled by the conjoint action of said relays,and a line signal out-oil relay for each line energized in series withone of said relays.

18. A telephone system comprising a pair of telephone lines, aninductive device through which the same areadapted to be united forconversation, a charging source of electricity and two pairs of relaysbetween the two limbs of said lines, whereby the source of current is inbridge ot the talking circuit, one pair of relays being individual toone of said lines and the other pair being individual to the other line,switches at the substations and at the central station for controllingthe circuit through said rclays, a signal controlled by the conjointaction of each pair of relays, and a line signal cut-oil relay for eachline energized in series with one of said relays.

19. In a telephone system, a metallic telephone line, an operators plugand a cord circuit, a source of current and a pair of relays placed bythe cord circuit between the terminals of said line, a third conductorconnected with one pole of said source, one of said relays being adaptedto be operated over the metallic line when the subscribers telephone isin use, and t-he other to be operated over a part of the line and saidthird conductor when the subscribers telephone is not in use and theoperators plug is connected with the line, and a line signalcutoit relayfor each line energized in series with one of said relays. i

20. In a telephone system, a telephone line, a source of current and arelay inserted between the two limbs of said line, to bridge the sourceof current across the talking circuit, a second relay at the centraloflice and connected with one side of the talking circuit and means forenergizing it, a switch at the substation and a switch at the centralstation for controlling the circuit through said relays, a signalcontrolled by the conjoint action of said relays,-and a line signalcut-off relay for each line energized in series with one of said relays.

21. In a telephone system, a telephone line, a source of electricity atthe central oiiice, an operators plug and a pair of relays associatedtherewith, one of said relays being energized from the said source ofelectricity while the plug is connected with the said line and over apath having a part coincident with the talking circuit, and the otherrelay being energized while the plug is connected with the said line andthe subscribers telephone is in use, a signal associated with said pairof relays, the circuit of said signal being established by the operationof the first of said relays and said signal being rendered inoperativeby the operation of the second of said relays, and a line signal cut-offrelay for each line energized in series with one of said relays.

22. In a telephone exchange system, telephone lines extending fromsubstations to an exchange, each of said substations being provided witha telephone switch hook for supporting the receiver thereat. a commonbattery at the exchange, supervisory signals located at the exchange,corresponding to calling and called subscribers stations, supervisoryrelays at the exchange, one for each of the supervisory signals, meanswhereby the switch hooks at the subscribers stations are adapted tooperate each of said relays independently of the other to actuate thecorresponding indicator, a second supervisory relay associated with eachsupervisory signal adapted through the agency of the switch hooks torestore the supervisory signals each independently of the other, meanswhereby the latter relays are both actuated independently of each otherby the said switch hooks, and a line signal cut-oliE relay for each lineenergized in series with one of said relays, said relays all energizedover circuits including portions of the talking circuit.

23. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby through the agency ofthe substation apparatus, a local circuit for each telephone line toinclude the said source of current in a local circuit, one relay of eachpair that is controlled by a subscribers station apparatus beingincluded in the corresponding local circuit, whereby one relay of eachpair may place the supervisory signal in one condition of use, and bothrelays cooperating place the supervisory signal in another condition ofuse, and a line signa-l cut-oli relay for each line energized in serieswith one of said relays.

2li. ln a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, switching apparatusfor controlling the operation of the relays, a reactive device includedin each cord strand between the connections of the relays therewith, anda line signal cut-ott relay for each line energized in series with oneof said relays.

25. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming' connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, a local circuit foreach telephone line to include the said source of current in a localcircuit, one relay of each pair being included in the correspondinglocal circuit, whereby one relay of each pair may place the supervisorysignal in one condition of use, and both relays coperating place thesupervisory signal in another condition of use, and a line signalcut-olf relay for each line energized in series withone of said relays.

26. ln a telephone system, telephonelines extending from substations tojacks at an exchange, a cord circuit at the exchange provided with twostrands for forming connections between subscriberslines, a pair ofrelays corresponding to each end of the cord circuit, a source ot'current for energizing the said relays, connected in bridge of thetalking circuit, a supervisory signal for each pair of relays andjointly controlled thereby, switching mechanism at the substations forcontrolling the operation ot one ot each pair of relays, means includinga jack and a cord circuit plug inserted in the jack, whereby a closedcircuit is established through the remaining relay of each pair which isindependent of the operative position ot the substation apparatus,areactive device included in each cord strand between the connections ofthe relays therei with, and a line signal cut-oilE relay for each lineenergized in series with one of said relays.

27. A. telephone system comprising a telephone line, a source of currentand a relay inserted between the two limbs of said line, a second relayand means for energizing it over a circuit including part of the talkingcircuit, a switch at. the substation and a switch at the central stationfor controlling the circuit through said relays, a signal controlled bythe conjoint action of said relays, a line signal, and means whereby theflow of current in one of said relays serves to retire the said linesignal.

28. A telephone system comprising a telephone line, a source of currentand a relay inserted between the terminals of the two limbs of saidline, a second relay and means for energizing it over a circuitincluding part of the talking circuit, a switch at the substation forcontrolling said bridged relay and a switch at the central otlice forcontrolling said other relay, a signal controlled by the conjoint actionof said relays, a line signal, and means whereby the flow of cur` rentin one'of said relays serves to retire the said line signal.

29. A telephone system comprising a telephone line, a source of currentand an electromagnet inserted between the terminals of the two limbs ofsaid line, a second electromagnet and means for energizing it over acircuit including part of the talking circuit, a switch at thesubstation and a switch at the central station for controlling thecircuit through said electro-magnets, a supervisory signal controlled bythe joint action of said electro-magnets, a line signal, and meanswhereby the flow of current in one of said relays serves to retire thesaid line signal.

30. A telephone line comprising a source of electricity and a pair ofrelays adapted to be inserted between the limbs of said line, to placethe source of current in bridge of the talking circuit, a switch at thesubstation and a switch at the central station for controlling thecircuit through said relays, a signal adapted to be cont-rolled by t-heconjoint action of said relays, a line signal, and means whereby theflow of current in one of said relays serves to retire the said linesignal.

3l. A telephone system comprising a pair of telephone lines, aninductive device through which the same are adapted to be united forconversation, a charging source ot electricity and a pair of relaysadapted to be inserted between the two limbs of each of said lines, toplace the source of current in bridge of the talking circuit, one pairof relays being individual to one of said lines and the other pair beingindividual to the other line, switches at the substations and at thecentral station for controlling the circuitthro-ugh said relays, asignal controlled by the conjoint action oi each pair of relays, a linesignal, and means whereby the flow ot current in one of said relaysserves to retire the said line signal.

32. In a telephone system, a metallic telephone line, an operators plugand a cord circuit, a source of current and a pair of relays bridged bythe cord circuit between the limbs ot said line, a third conductor`connected with one pole of said source, one of said relays beingadapted to be operated over the metallic line when the subscriberstelephone is in use, and the other to be operated over a part of theline and said third conductor when the subscribers telephone is not inuse and the operators plug is connected with the line, a line signal,and means whereby the flow of current in one of said relays serves toretire the said line signal.

33. ln a telephone system, a telephone line, a source of current and arelay bridged between the terminals of the two limbs of said line, asecond relay at the central oiiice and connected with one side of thetalking circuit and means for energizing it, a switch at the substationand a switch at the central station for controlling the circuit throughsaid relays, a signal controlled by the con joint action of said relays,a line signal, and means whereby the flow of current in one of saidrelays serves to retire the said line signal,

34. In a telephone system, a telephone. line, a source of electricity atthe central otlice, an operators plug and a pair of relays associatedtherewith, one of said relays being energized from the said source otelectricity while the plug is connected with the said line and over apath having a part coincident with the talking circuit, and the otherrelay being energized while the plug is connected with the saidline andthe subscribers telephone is in use, a signal associated with said pairof relays, the circuit of said signal being established by the operationof the first of said relays and said signal being renderedinoperative bythe operation of the second ot said relays, a line signal, and meanswhereby the flow ot current in one of said relays serves to retire thesaid line signal.

35. In a telephone exchange system, telephone lines extending fromsubstations to an exchange, each of said substat-i ons being pro videdwith a telephone switch hook for supporting the receiver thereat, acommon battery at the exchange, supervisory signals located at theexchange, corresponding to calling and called subscribers stations,supervisory relays at the exchange, one for each of the supervisorysignals, means whereby the switch hooks at the subscribers stations areadapted to operate each of said relays independently of the other toactuate the corresponding indicator, a second supervisory relayassociated with each supervisory signal adapted through the agency ofthe switch hoo-ks to restore the supervisory signals each independentlyof the other, means whereby the latter relays are both actuatedindependently of each other by the said switch hooks, a line signal, andmeans whereby the flow of current in one of said relays serves to retirethe said line signal, said relays all energized over circuits includingportions of the talking circuit.

36. In a telephone system, telephone lines extending from subscribers7stations to an exchange, a cord circuit at the exchange provided withtwo strands tor forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs ot relays,connected in bridge oi the talking circuit, a supervisory signal foreach pair ofrelays and jointly controlled'thereby through the agency ofthe substation apparatus, a local circuit for each telephone line toinclude the said source of current in a local circuit, one relay ot eachpair that is controlled by a subscribers station apparatus beingincluded in the corresponding local circuit, whereby one relay of eachpair may place the supervisory signal in one condition of use, and bothrelays coperating place the supervisory signal in another condition ofuse, a line signal, and means whereby the iiow of current in one of saidrelays serves to retire the said line signal. y

37. In a telephone system, telephone lines extending from subscribersstations to an ex change, a cord circuit at the exchange pro- Clt videdwith two strands for forming connections, between two telephone lines, apair of relays corresponding to each end ot' the cord circuit, a sourceof current for inclusion in' circuit with each o t said pairs of relays,connected in bridge ot' the t-alking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, switching apparat-usfor controlling the operation of the relays, a reactive device includedin each cord st-rand between the connections of the relays therewith, aline signal, and means whereby the iow of current in one of said relaysserves to retire the said line signal.

38. 1n a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairot relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, a local circuit t'oreach telephone line to include the said source of current in a localcircuit, one relay of each pair being included in the correspondinglocal circuit, whereby one relay of each pair may place the supervisorysignal in one condition of use, and both relays cooperating place thesupervisory signal in another condition of use, a line signal, and meanswhereby the iiow of current in one of said relays serves to retire thesaid line signal.

39. In a telephone system, telephone lines extending from substations tojacks at an exchange, a cord circuit at the exchange provided with twostrands for forming connections between subscribers lines, a pair ofrelays corresponding to each end of the cord circuit, a source ot'current for energizing the said relays, connected in bridge of thetalking circuit, a supervisory signal for each pair ot relays andjointly controlled thereby, switching mechanism at the substations forcontrolling the operation of one of each pair of relays, means includinga jack and a cord circuit plug inserted in the jack, whereby a closedcircuit is established through the remaining relay of each pair which isindependent ot the operative position of the substation apparatus, areactive device included in each cord strand between the connections of.the relays therewith., a line signal, and means whereby the flow ofcurrent in one of said relays serves to retire the said line signal.

l0. A telephone system comprising a telephone line, a source of currentand a relay inserted between the terminals of the two limbs ot saidline, a second relay and means for energizing it over a circuitincluding part of the talking circuit, a switch at the substation and aswitch at the central stat-ion for controlling the circuit through saidrelays, a signal controlled by the conjoint action of said relays, andmeans for rin-ging over the two sides of the called line in series.

4l. A telephone system comprising a telephone line, a source of currentand a relay inserted between the terminals of the two limbs et saidline, a second relay and means for energizing it over a circuitincluding part ot' the talking circuit, a switch at the substation forcontrolling said bridged relay and a switch at the central otlice forcontrolling said other relay, a signal controlledV by the conjointaction of said relays, and means for ringing over the two sides of thecalled line in series. f

42. A telephone system comprising a telephone line, a source of currentand an electro-magnet inserted between the terminals of the two limbs otsaid line, a second electro-magnet and means for energizing it over acircuit including part of the talking circuit, a switch at thesubstation and a switch at the central station for controlling thecircuit through said electro-magnets, a supervisory signal controlled bythe joint action of said electro-magnets, and means for ringing over thetwo sides of the called line in series.

43. A telephone line comprising a source of electricity and a pair ofrelays adapted to be placed between the terminals ot the two limbs ofsaid line, a switch at the substation and a switch at the centralstation tor controlling the circuit through said relays, a signaladapted to be controlled by the conjoint action of said relays, andmeans for 'ringing over the two sides of the called line in series.

4A. A telephone system comprising a pair of telephone lines, laninductive device through which the same are adapted to be united forconversation, a charging source of electricity and two pairs of relaysadapted to be placed between the terminals of the two limbs of each ofsaid lines, one pair of relays being individual to one of said lines andthe other pair being individual to the other line, switches at thesubstations and at the central station for controlling the circuitthrough said relays, a signal controlled by the conjoint action of eachpair ot relays, and means for ringing over the two sides of the calledline in series. l

15. In a telephone system, a metallic telephone line, an operators plugand a cord circuit, a source of current and a pair of relays bridged bythe cord circuit across the terminal of said line, a third conductorconnected with one pole of said source, one of said relays being adaptedto be operated over the metallic line when the subscribers telephone isin use, and the other to be operated over a part of the line and saidthird conductor when the subscm'bers telephone is not in use and theoperators plug is connected with the line, and means for ringing overthe two sides of the called line in series.

46. ln a telephone system, a telephone line, a source or" current and arelay bridged between the two terminals ot' the two limbs of said line,a second relay at the central otlice and connected with one side of thetalking circuit and means for energizing it, a switch at the substationand a switch at t-he central station for controlling the circuit throughsaid relays, a signal controlled by the conjoint action of said relays,and means for ringing over the two sides of the called line in series.

47. ln a telephone system, a telephone line, a source of electricity atthe central oltice, an operators plug and a pair of relays associatedtherewith, one of said relays being energized from the said source ofelectricity while the plug is connected with the said line and over apath having a partcoincident with the talking circuit, and the otherrelay being energized while the plug is connected with the said line andthe subscribers tele-phone is in use, a signal associated with said pairof relays, the circuit of said signal being established by the operationof the first of said relays and said signal being rendered inoperativeby the operation of the second o' said relays, and means for ringingover the two sides of the called line in series.

4S. In a telephone exchange system, telephone lines extending fromsubstations to an exchange, each or' said substations being providedwith a telephone switch hook for supporting the receiver thereat, acommon battery at the exchange, supervisory signals located at theexchange, corresponding to calling and called subscribers stations,supervisory relays at the exchange, one for each of the supervisorysignals, means whereby the switch hooks at the subscribers stations areadapted to operate each of said relays independently of the other toactuate the corresponding indicator, a second supervisory relayassociated with each supervisory signal adapted through the agency ofthe switch hooks tc restore the supervisory signals each independentlyof the other, means whereby vthe latter relays are both actuatedindependently of each other by the said switch hooks, and means :torringing over the two sides of the called line in series, said relays allenergized over circuits including portions of the talking circuit.

49. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairet relays corresponding to each end of the cord circuit, a source otcurrent for inclusion in circuit .vith each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby controlled by asubscriber-s station apparatus, a local circuit for each telephone lineto include the said source oi current in a local circuit, one relay ofeach pair that is cont-rolled by a subscribers station apparatus beingincluded in the corresponding local circuit, whereby one relay of eachpair may place the supervisory signal in one condition of use, and bothrelays cooperating place the supervisory signal in another condition ouse, and means for ringing over the two sides of the called line inseries.

50. In a. telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtw'o strands for forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, switching apparatusfor controlling the operation of the relays, a reactive device includedin each cord strand between the connections of the relays therewith, andmeans for ringing over t-he two sides of the called line in series.

5l. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected inbridge of the talking circuit, a supervisory signal for eachpair of relays and jointly controlled thereby, a local circuit for eachtelephone line to include the said source of current in a local circuit,one relay of each pair being included in the corresponding localcircuit, whereby one relay of each pair may place the supervisory signalin one condition of use, and both relays coperating place thesupervisory signal in another condition of use, and means for ringingover the two sides of the called line in series.

52. In a telephone system, telephone lines extending Vfrom substationsto jacks at an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between subscribers lines, a pair ofrelays corresponding to each end of the cord circuit, a source ofcurrent for energizing the said relays, connected in bridge of thetalking circuit, a supervisory signal for each pair of relays andjointly controlled thereby, switching mechanism at the substations forcontrolling the operation of one of each pair of relays, means includinga jack and a cord circuit plug inserted in the jack, whereby a closedcircuit is established through the remaining relay oit' each pair whichis independent ot the operative position of the substation apparatus, areactive device included in each cord strand between the connections ofthe relays therewith, and means for ringing over thc two sides of thecalled line in series.

53. A telephone system comprising a telephone line, a source ot currentand a relay connecting together the two limbs o1t` said line, so thatthe battery is in bridge ot tho talking circuit, a second relay andmeans for energizing it over a circuit including part of the talkingcircuit, a switch at the substation and a switch at the central stationfor controlling the circuit through said relays, a signal controlled bythe conjoint action of said relays, and a busy test circuit includingone of said relays.

A telephone system comprising a telephone line, a source ot current anda relay connecting together the two limbs of said line, so that thebattery is in bridge of the talking circuit, a second relay and meansfor energizing it over a circuit including part of the talking` circuit,a switch at the substation for controlling' said bridged relay and aswitch at the central othce for controlling said other relay, a signalcontrolled by the conjoint action ot said relays, and a busy testcircuit including one of said relays.

A telephone system comprising a telephone line, a source of current andYan electro-magnet connecting together the two limbs of said line, asecond electro-magnet and means for energizing' it over a circuitincluding part of the talking circuit, a switch at the substation and aswitch at the central station for controlling the circuit through saidelectro-magnets, a supervisory signal controlled by t-he joint action ofsaid electro-magnets, and a busy test circuit including one of saidrelays.

56. A telephone system comprisinga line, a source of electricity and apair of relays adapted to be placed between the limbs ot said line, aswitch at the substation and a switch at the central station forcontrolling the circuit through said relays, a signal adapted to becontrolled by the conjoint action of said relays, and a busy testcircuit including one of said relays.

57. A telephone system comprising apair of telephone lines, an inductivedevice through which the same are adapted to be united for conversation,a charging source of electricity and a pair of relays adapted to beplaced between t-he two limbs of each of said lines, one pair of relaysbeing for one of said lines and the other pair being for the other line,switches at the substations and at the central station for controllingthe circuit through said relays, a signal controlled by the conjointaction of each pair of relays, and a busy test circuit including one ofsaid relays.

58. In a telephone system, a metallic telephone line, an operators plugand a cord circuit, a source of current and a pair of relays placed bythe cord circuit between the terminals of said line, a third conductorconnected with one pole of said source, one of said relays being adaptedto be operated over the metallic line when the subscribers telephone isin use, and the other to be operated over a part of the line and saidthird conductor when the subscribers telephone is not in use and theoperators `,plug is connected with the line, and a busy test circuitincluding one of said relays.

59. In a telephone system, a telephone line, a source ot current and arelay placed between the two limbs of said line, a second relay at thecentral ottice and connected with one side of the talking circuit andmeans for energizing it, a switch at the substation and a switch at thecentral station for control-V ling the circuit through said relays, asignal controlled by the conjoint action of said relays, and a busy testcircuit including one of said relays.

60. In a telephone system, a telephone line, a sourceV of electricity atthe central otiice, an operato-rs plug and a pair of relays associatedtherewith, one ot said relays being energized from the said source ofelectricity while the plug is connected with the said line and over apath having a part coincident with the talking circuit, and the otherrelay being energized while the plug is connected with the said line andthe subscribers telephone is in use, a signal associated with said pairof relays, the circuit of said signal being established bythe operationof the tirst of said relays and said signal being rendered inoperativeby the operation of the second of said relays, and a busy test circuitincluding one of said relays.

61. In a telephone system, telephone lines extending from substations toan exchange, each of said substations being provided with a telephoneswitch hook for supporting the receiver thereat, a common battery at theexchange, supervisory signals located at the exchange, Vcorresponding tocalling and called subscribers stations, supervisory relays at theexchange, one for each of the supervisory signals, means whereby theswitch hooks at the subscribers stationsl are adapted to operate each ofsaid relays independently ot the other to actuate the correspondingindicator, a second supervisory relay associated with each supervisorysignal adapted through the agency of the switch hooks to restorethesupervisory signals each independently of the other, means wherebythe latter relays are both actuated independently of each other by thesaid switch hooks, and a busy test circuit including one of said relays.

62. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming coni nections between two telephone lines, apair of relays corresponding to each end of the cord circuit, a sourceof current for inclusion in circuit with each of said pairs of relays,connected by the relays in bridge of the talking circuit, a supervisorysignal for each pair of relays and jointly controlled thereby throughthe agency of the substation apparatus, a local circuit for eachtelephone line to include the said source of current in a local circuit,one relay of each pair that is controlled by a subscribers stationapparatus being included in the corresponding local circuit, whereby onerelay of each pair may place the supervisory signal in one condition ofuse, and both relays coperating place the supervisory signal in anothercondition of use, and a busy test circuit including one of said relays.

G3. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, switching apparatusfor controlling the operation of the relays, a reactive device includedin each cord strand between the connections of the relays therewith, anda busy test circuit including one of said relays.

G4. In a telephone system, telephone lines extending from subscribersstations to an exchange, a cord circuit at. the exchange provided withtwo strands for forming connections between two telephone lines, a pairot relays corresponding to each end of the cord circuit, a source ofcurrent for inclusion in circuit with each of said pairs ot' relays,connected in bridge ot the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, a local circuit foreach telephone line to include the said source of current in a localcircuit, one relay of each pair being included in the correspondinglocal circuit, whereby\ `one relay of each pair may pl'ace thesupervisory signal in one condition of use, and both relays coperatingplace the supervisory signal in another condition of use, and a busytest circuit including one of said relays.

lli.

65. In a telephone system, telephone lines extending from substations tojacks at an exchange, a cord circuit at the exchange provided with twostrands for forming connections between subscribers lines, a pair ofrelays corresponding to each end of the cord circuit, a source ofcurrent for energizing the said relays, connected in bridge of thetalking circuit, a supervisory signal Jfor each pair ot' relays andjointly controlled thereby, switching mechanism at the substations forcontrolling the operation of one of each pair of relays, means includinga jack and a cord circuit plug inserted in the jack, whereby a closedcircuit is established through the remaining relay of each pair which isindependent of the operative position of the substation apparatus, areactive device included in each cord strand between the connections ofthe relays therewith, and a busy test circuit including one of saidrelays.

6G. A telephone system comprising a telephone line, a source of currentand a relay bridged between the two line terminals of the limbs of saidline, a second relay and means for energizing it over a circuit including part of the talking circuit, a switch at the substation forcontrolling said bridged relay and a switch at the central oiiice forcontrolling said other relay, and a signal controlled by the conjointaction of said relays.

67. In a telephone system, telephone lines extending from subscribers7stations to an exchange, a cord circuit at the exchange provided withtwo strands for forming connections between two telephone lines, a pairof relays corresponding to each end of the cord circuit, a source ofcurrent for inclu sion in circuit with each of said pairs of relays,connected in bridge of the talking circuit, a supervisory signal foreach pair of relays and jointly controlled thereby, and a local circuitfor each telephone line to include the said source of current in a localcircuit, one relay of each pair being included in the correspondinglocal circuit, whereby one relay of each pair may place the supervisorysignal in one condition of use, and both relays cooperating place thesupervt sory signal in another condition of use.

68. In a telephone system, the combination with a pair of telephonelines, of a cord circuit to connect said lines for conversation, callingand answering supervisory signals for said cord circuit, tour relays,one located in each end of each talking strand of the cord circuit, thecircuit of each of said signals being completed through contactscontrolled by two ot said relays, switches under the control of theoperator in the circuit of two of said relays, the actuation of saidrelays being adapted to close the circuits of said supervisory signals,switches under the control of the subscribers in the circuits of theother two of said relays, said relays being adapted when actuated toopen the circuits of said supervisory signals, substantially asdescribed.

69. ln a telephone system, the combination with a pair of telephonelines, oil a cord cil-crit te connect said lines for conversation,calling and answering supervisory signals for said cord circuit, fourrelays, one l0- cated in each end of each talking` strand of the cordcircuit, switches under the control of the operator in the Circuit oftwo of said relays, the actuation of said relays being` Signed by nie atAtlantic City, Atlantic county, New Jersey, this 1st day of `archCHARLES L. GOODRUM.

vWitnesses z ARTHUR VRIGHT, J. S. CARRINTH.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of atents. Washington, D. C.

